ok, nandini was married to ansh, who was really tulsi and mihir's son but was separated from them and raised by aditya gujral; ansh raped nandini and would kill her if tulsi hadn't killed him; tulsi went to jail for three years; fast forward a bit more and aditya gujral is back, and he bothers the viranis a lot by taking over their company, etc. and says he will stop doing it b/c he wants ansh's and nandini's daughter bhumi; nandini is livid and thus kills him and goes to jail for 14 years; while she was in jail before leap, we found out that ansh actually had a first wife (i forget her name) and a son eklayva with him; however, she had a hole in her heart and so she left him so he wouldn't have to suffer her early death; she didn't know she was pregnant at the time, but she raised her child eklaya till he was like 6; then she died and tulsi took him hom b/c she knew he was ansh's son
hope that helps!